a-a a-c aaa aac aaf aan aar ac- aca acc acf acn acr af- afa afc aff afn afr an- ana anc anf ann anr ar- ara arc arf arn arr c-- caa cac caf can car cca ccc ccf ccn ccr cfa cfc cff cfn cfr cn- cna cnc cnf cnn cnr cra crc crf crn crr faa fac faf fan far fca fcc fcf fcn fcr ffa ffc fff ffn ffr fna fnc fnf fnn fnr fra frc frf frn frr naa nac naf nan nar nca ncc ncf ncn ncr nfa nfc nff nfn nfr nna nnc nnf nnn nra nrc nrf nrn nrr ra- raa rac raf ran rar rca rcc rcf rcn rcr rfa rfc rff rfn rfr rna rnc rnn rnr rra rrc rrf rrn rrr